A touch sensor is known as an interface for users to input information into a display device. By arranging a touch sensor so as to overlap the screen of a display device, users may control input buttons, icons, and the like displayed on the screen, and may easily input information into the display device.
A display device having a touch sensor must accurately detect places which have been touched. However, there is a phenomenon called “ghost touch,” in which a place other than a place that has been touched is detected. For example, in Japanese Laid-Open Patent Publication Number H11-194893, a method for detecting touched places using electrodes in two directions of columns and rows is disclosed. In Japanese Laid-Open Patent Document Number 2015-184888, a liquid crystal display device reducing the influence of ghost touch is disclosed.